The enormous variety of biochemical reactions that comprise life are nearly all mediated by a series of biological catalysts known as enzymes. Enzymes are proteins which possess specific catalytic activities that enable them to catalyze a series of reactions, hence enabling metabolic pathways to degrade and to reconstruct products needed to maintain organisms. By the binding of substrates through geometrically and physically complementary reactions, enzymes are stereospecific in binding substrates as well as in catalyzing reactions. The stringency for this stereospecificity varies as some enzymes are more specific to the identity of their substrates, while others are capable of binding multiple substrates and can catalyze numerous types of reactions.
Examples of enzymes include, for example, phospholipases, serine carboxypeptidases, trypsin-like serine proteases, aldehyde dehydrogenases, ubiquitin-protein ligases, protein kinases, hydrolases and matrix metalloproteinases. Such enzymes have the ability to, for example: to reversibly phosphorylate proteins in order to regulate protein activity in eukaryotic cells; to catalyze the hydrolysis of an acyl or phosphoacyl bond of a phospholipids; to modulate removal of COOH-terminal residues, i.e., having carboxypeptidase activity; to modulate the transfer of an acyl group from a donor to an acceptor molecule, i.e., having acyltransferase activity; to degrade proteins; to phosphorylate carbohydrates; to oxidate an aldehyde; to modulate ubiquitination of a substrate, e.g., a protein targeted for degradation; to modulate substrate specificity for ubiquitination; to reversibly phosphorylate proteins in order to regulate protein activity in eukaryotic cells; to interact with cytotoxins and metabolites (e.g., lactoylglutathione, a glutathione-conjugated metabolite, a hydroxycarboxylic acid, and the like); to catalyze the metobolism of a cytotoxin or metabolite; to hydrolyze a thioester containing compound (e.g., lactoylglutathione, and the like); to catalyze the formation of a thioester conjugation on a substrate (e.g., lactate or a hydroxycarboxylic acid); to cleave or modulate the degredation of proteins or peptides of the extracellular matrix; to catalyze or modulate catalysis of cleavage of covalent bonds within or between amino acid residues (e.g., in extracellular matrix, cell-surface, and extracellular proteins); as well as many others. Accordingly, there exists a need to identify additional human enzymes, for example, for use as disease markers and as targets for identifying various therapeutic modulators.